This is a tricky diagnosis because I don't really know how to describe the noise I am having. From 2500-3000 rpm the power drops a little and a noise that sounds like ignition ping, but faster :? . Over 3,000 it pulls like normal again and the noise is gone. With gas prices I would really prefer to stay below 3000 in normal conditions, and 2500 isn't working out the best. The noise happens EVERY time in this range and either warm or cold. Below is a list of new items, this problem occured before and after the changes.

New plugs and wires
Delco Ignition
O2 Sensor

Two of the plugs had a fair amount of crud (medium brown, not oil) built up, the rest looked like new. Any ideas are welcome!

Sounds like it may be an accessory going out.. try removing the serpentine belt, and see if that noise still persists. Don't do this with a warm engine. You will lose your Water Pump during this, along with Power Steering, Alternator, and A/C. Just for clarification. Try not to run the engine more than 5 minutes in this condition. If you cannot reproduce the noise with the car sitting, you can drive her a little, but the 5 minutes stands, IMO. I wouldn't feel safe past that.

If that doesn't change anything, try the old screw driver on your ear trick, and see if you can find where it may be coming from. Use an extra long flat head. That seems to work best for me.


-justin

The engine only makes the noise under load (driving). I have a stethoscope and there are no noises at idle, or around 2700 RPM without any load on the engine. I wouldn't think that an accessory would stop making noise at higher RPM'* either... but time will tell. It has been doing this for about 500 miles, which is one of the reasons I replaced all that I did.

Thanks for the input.

If its just a plain old noise check the heat sheilds on the exhaust manifold by the 02
sensor and on the cat. They tend to rot out and rattle at certain RPM'*.
I had to put a stainless hose clamp around my manifold to stop the rattle.
Everything is quiet now.

TPS maybe?